Bergamaschi Greta, Boiocchi Massimo, Perrone Maria Lucia, Poggi Antonio, Viviani Ivan, Amendola Valeria
Dipartimento di Chimica, Università di Pavia, via Taramelli 12, I-27100, Pavia, Italy.
Dalton Trans. 2014 Aug 7;43(29):11352-60. doi: 10.1039/c4dt00886c. Epub 2014 Jun 13.
In this work, we report on two new asymmetric dicopper cryptates, characterized by alternate furanyl and p-xylyl spacers. The results of the potentiometric, UV-vis and X-ray diffraction studies are discussed. In particular, for one of the cages in the octaprotonated form, the crystal structure of the complex with nitrate is described. From the point of view of the anion binding in water, the new dicopper cryptates display stronger similarities to each other than to the symmetric analogues (i.e. p-xylyl and furan cryptates). The substitution of even only one spacer modifies the distance between the metal ions. This prevents the development of the CT band, typically accompanying the binding of halides by the furan cryptate, and favors the formation of complexes of different stoichiometry with the linear azide anion, not observed for the symmetric cryptates. The obtained results may be very helpful in the design of new molecular receptors based on dimetallic cryptates, in particular for the tuning of the sensitivity towards specific anionic substrates.
在本研究中，我们报道了两种新型不对称双铜穴状配合物，其特征在于含有交替的呋喃基和对二甲苯基间隔基团。讨论了电位滴定、紫外可见光谱和X射线衍射研究的结果。特别地，对于其中一种呈八质子化形式的笼状配合物，描述了其与硝酸盐形成的配合物的晶体结构。从阴离子在水中的结合情况来看，新型双铜穴状配合物彼此之间的相似性比与对称类似物（即对二甲苯基和呋喃穴状配合物）更强。即使仅替换一个间隔基团也会改变金属离子之间的距离。这阻止了通常伴随呋喃穴状配合物与卤化物结合而出现的电荷转移带的形成，并有利于与线性叠氮阴离子形成不同化学计量比的配合物，而对称穴状配合物则未观察到这种情况。所获得的结果对于基于双金属穴状配合物的新型分子受体的设计可能非常有帮助，特别是在调节对特定阴离子底物的敏感性方面。
